<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        html {
            min-height: 100%;
            background: #172f38;
            color: #d7dbdd;
            margin: 0;
            padding: 20px;
            cursor: pointer;
            box-sizing: border-box;
        }

        body {
            margin: 0;
        }

        .container span {
            float: left;
            min-width: 2em;
            margin-right: 10px;
        }

        .center {
            position: fixed;
            left: 50%;
            top: 50%;
            font-size: 8em;
            color: rgba(255, 255, 255, .7);
            transform: translate(-50%, -50%);
            /* 针对opactiy，变化函数使用ease-in，延迟0.3s变化，变化时在0.7s完成
               针对其他css属性，变化函数使用ease-in，变化总时间1s
             */
            transition: all 1s ease-in, opacity 0.7s ease-in 0.3s;
        }
    </style>
</head>

<body>
    <div id="divContainer" class="container">
    </div>
    <div id="divCenter" class="center">
    </div>

    <script src="main.js"></script>
</body>

</html>